und mechanisches Verhalten des Schaumglases
von Dr. sc. techn. ETH Rudolf Trinkner


This dissertation was compiled in conjunction with a research project, the aim of which was to produce from old glass, structural foam glass blocks with excellent thermal insulation properties. We found a method which enables us to produce foam glass from a mixture of pulverized old glass and a bloating substance at high temperature. Depending on the various methods of bloating different types of foam glass were obtained.

Using thin transparent slices and volumetric measurements, the microstructure of these foam glasses was examined. Morphologically, we can differentiate between spherical foam glass and polyhedral foam glass! Special mention must be made of relationships (regressions) found between the density (ρ) and the size of pores (L̅3), as well as between the densitiy and internal gas distribution (n,n) in polyhedral foam glass.

In spite of the many different shapes of polyhedron cell bubbles, it was possible to find a model which illustrates satisfactorily the internal load bearing structure of the polyhedral foam glass. This model corresponds quite closely to J. Plateau's principles of fluid foams.

In the model foam glass (TOP) discovered in this way, a relationship between its external loads and the stress conditions on its polyhedral bubble surfaces was found by using numerical stress analysis.

Based on the foregoing relation, the mechanical properties of polyhedral foam glass in relation to its density could be predicted satisfactorily by means of a hypothesis of fracture on the surface.

The fracture resistances (σdBBB) and elastic properties (E,ν) found were compared with the values measured with foam glass test specimens. It was found that there is a satisfactory correspondence between the predicted values and those measured with the actual test specimens.

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